在一个方框图形中添加一些标题

Question

我想做这样的标题

参见（a）和（b）。我不知道如何添加到我的图中。我只有这样的

不同之处仅在于此

这是 MWE

 \documentclass[a4paper, 12pt, twoside,demo]{book}
    \usepackage{pdfpages}
    \usepackage{pslatex}%
    \usepackage{setspace}
    \setlength{\abovecaptionskip}{1pt}
    \usepackage[paperheight=297mm,paperwidth=215mm,top=3cm,left=4cm,bottom=3cm,right=3cm]{geometry}


    \usepackage{graphicx}

    \usepackage{eqparbox} %membuat spasi chapter rata

 \begin{document}
 \begin{figure}[h!]
 \centering
  \fbox{%
    \begin{minipage}{\dimexpr12cm-2\fboxsep-2\fboxrule}\centering
     \includegraphics[scale=0.3]{kurvaeta2.png}
     \includegraphics[scale=0.4]{kurvaetamatlab.png}
     \caption{Perbandingan Kurva Kekentalan Mikroalga terhadap Posisi} \label{bab2g1}
    \end{minipage}}
 \end{figure}
 \end{document}

Answer 1

\documentclass[12pt, twoside, demo]{book}
\usepackage[paperheight=297mm,paperwidth=215mm,
            hmargin={4cm,3cm}, vmargin=3cm]{geometry}
\usepackage{graphicx}
\usepackage{subcaption}

 \begin{document}
 \begin{figure}[ht]
    \centering
\begin{subfigure}{0.45\linewidth}
\includegraphics[width=\linewidth]{kurvaeta2.png}
    \caption{}
    \label{subfig:a}
\end{subfigure}
    \hfil
\begin{subfigure}{0.45\linewidth}
\includegraphics[width=\linewidth]{kurvaetamatlab.png}
    \caption{}
    \label{subfig:b}
\end{subfigure}
     \caption{Perbandingan Kurva Kekentalan Mikroalga terhadap Posisi} 
     \label{bab2g1}
 \end{figure}
 \end{document}